Perhaps it was the third goal, scored by David Alaba, which best summed up the red tide that engulfed frail and depleted Arsenal.

Left back Alaba was roaming in an area usually occupied by a central striker when he muscled the ball from Santi Cazorla, then turned and worked it on to his left foot before lashing it into the top corner.

It was just before half-time and Bayern Munich were rampant, swarming forth from all angles, swaggering, an irresistible force.

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Robert Lewandowski is left entirely unmarked close to the Arsenal goal as he heads Bayern Munich ahead after just 10 minutes

The Polish striker celebrates after breaking the deadlock, having escaped a poorly executed Arsenal offside trap

Thomas Muller celebrates making it 2-0, after his close-range shot was deflected past Petr Cech off the leg of Per Mertesacker

Mesut Ozil asks questions of his defence as Bayern celebrate their second goal, and Cech looks concerned

David Alaba makes it 3-0 before half time with a brilliant long-range strike which sails over Petr Cech and into the top corner of the net

The Austrian left back was clearly delighted with his excellent strike, which put Bayern out of sight before the break

Arjen Robben fires past a diving Gabriel and into the roof of the net to add a fourth goal as Bayern converted their dominance into goals

Robben celebrates his goal, his third of the season and first in Europe, after only recently returning to the side following an injury

Olivier Giroud produced a wonderful goal of his own to make it 4-1, but it was little more than a consolation for the Gunners

As Arsenal desperately tried to plug one leak, another sprang open elsewhere. It could have been anyone who scored. On this particular occasion it happened to be Alaba, reward for his fabulous over- lapping intent.

Somewhere along the way, it seemed Arsene Wenger’s team had made the Germans angry. Maybe it was the 2-0 win at the Emirates Stadium a fortnight earlier, or maybe it was the long-ball tactics they frowned upon. Or maybe it was when Mesut Ozil used his arm in an attempt to level at 1-1.

Revenge? Pep Guardiola called it ‘a cup final’. Arsenal had coaxed out the real Bayern for the opening 45 minutes in the Allianz Arena. The hosts led from Robert Lewandowski’s 10th-minute header. Thomas Muller made it two and Alaba crushed any realistic hopes of a fightback when he struck just before the interval.

Ten minutes after the restart, Arjen Robben scored with his first touch after coming on as a substitute.

Arsenal improved as Bayern relaxed and coasted home. Olivier Giroud pulled one back with an acrobatic volley, but Muller sped clear to grab the fifth, his second of the night in the 89th minute.

With three points from four European games, Wenger and his team have been issued with a brutal reminder of just how good the world’s best teams can be when they hit their stride. They have lost control of their destiny in this competition.

Giroud attempts to hold up the ball under pressure from Javi Martinez and Thiago Alcantara, but Arsenal struggled to keep possession

Douglas Costa congratulates his striker, whose goal put Bayern in complete control, as Arsenal failed to get to grips with their opponents

Olivier Giroud and Alexis Sanchez look up at the big screen, knowing that their task had just been made a whole lot harder

Arsene Wenger's frustration was obvious as his team failed to repeat their defensive heroics from the first game against Bayern

Mesut Ozil thought he had Arsenal back in the game at 1-1, but after the ball went in off his shoulder, it was disallowed

Manuel Neuer's vociferous complaints saw the referee consult his additional official, who ruled the goal out for handball

Ozil was booked for his attempt, and Arsenal rarely looked finding a way back into the game from that point on

Mertesacker stops Bayern's young winger Kingsley Coman with a crunching tackle, but the home side continued to dominate

All hope of qualifying for the last 16 is not lost, but to reach the knockout rounds from here, Arsenal must win their final two games — at home to Dinamo Zagreb and convincingly away at Olympiacos — and pray that the Greeks do not pick up an unexpected point in Munich.

A draw between Olympiacos and Bayern in the next game and the rare ignominy of Thursday night football in the Europa League will be staring Wenger in the face.

Will that hit their title bid? Will this result shatter the confidence of a threadbare squad?

The scale of Arsenal’s injury crisis was laid bare in Munich. With Laurent Koscielny and Hector Bellerin not fit to start, it took his casualty list of first-team players into double figures.

As Bayern brought Robben and Arturo Vidal on from the bench, Wenger sent on 19-year-old Alex Iwobi, Kieran Gibbs and Calum Chambers.

On the right, he started with Mathieu Debuchy and Joel Campbell in tandem, and they were at full stretch from the outset, ever vulnerable to the pace and energy of Kingsley Coman and Alaba.

Thiago Alcantara created the first from this area, given the time to pick out Lewandowski, who slipped away from Gabriel Paulista, adjusted well to the flight, arched his back and converted a deft header.

Petr Cech has to pick the ball out of his net for the second time after Muller's deflected strike beat him into the bottom right corner

Muller celebrates his goal, which almost ended the tie as a contest inside half an hour, as Arsenal crumbled in the Allianz Arena

Joel Campbell, who had to spend much of his evening tracking back to help his defence, puts in a tackle on Coman

Francis Coquelin slides in to stop Bayern's Brazilian star Douglas Costa breaking through the middle, but Arsenal's midfield was over-run

Alaba jumps for joy after his excellent strike further extend Bayern's lead, and leave Arsenal struggling to stay in the Champions League

The defender showed the strength Bayern have in all positions, scoring the pick of the goals from full back

Arsenal responded, although all was not as it appeared. Ozil, who started brightly, turned in Nacho Monreal’s cross at the near post. The officials, however, had spotted that he had used his upper arm.

Italian referee Gianluca Rocchi interrupted the celebrations to show Ozil a yellow card, the goal was ruled out and Bayern slipped back into the groove.

Petr Cech, back at the stadium where he performed heroics to win the Champions League with Chelsea in 2012, came under siege while, up front, Giroud was unable to relieve the pressure. Ozil was forced deeper and his influence faded.

Cech denied Coman and Lewandowski twice before Muller extended the lead. This time it was Philipp Lahm who swung it over from the right. The first effort, by Coman, was blocked but Muller pounced on the bouncing ball. His shot on the turn clipped Per Mertesacker on the shins and flashed inside the post.

Bayern were slicing through Arsenal at will, and the Allianz Arena was pulsating. Cech saved low and high to thwart Muller and Douglas Costa tested the goalkeeper from long range.

The visitors needed the sanctuary of the dressing room and Alaba’s strike was a killer blow, just before the break.

Philipp Lahm brings down Alexis Sanchez as the Arsenal star looked to get going on a rare foray forward for the Gunners

Cech gets down quickly to deny Lewandowski another goal, as Bayern threatened to run riot against Arsene Wenger's side

Ozil, who produced some flashes of brilliance in an otherwise frustrating night for Arsenal, takes on Douglas Costa on the left wing

Bayern captain Lahm shields the ball from Alexis Sanchez as the home side dominated both the ball and the scoreline in Munich

Lewandowski tries an overhead kick as the German champions turned on the style and bounced back from their defeat at the Emirates

Robben was brought off the bench early in the second half for the impressive Coman, and was on the scoresheet just seconds later

Cech could do nothing about the Dutch winger's close-range strike, which put his side four goals ahead

Alaba turned creator for the fourth, rolling a pass towards Robben, who sprinted across goal and fired it past Cech. Was this revenge for the penalty save three years ago? The Dutch winger had been on the pitch less than a minute.

Bayern relaxed and suddenly Wenger’s team went forward with renewed freedom and found gaps to exploit. A flick from Giroud sent Cazorla through but his volley was straight at Manuel Neuer. Monreal stormed forward but slipped and tumbled as he braced to shoot.

Giroud pulled one back, a mere consolation, before Muller compounded the misery on the break.

Arsenal's two German stars, Ozil and Mertesacker, look devastated as they took a pasting on their return to home soil

Giroud rushes to return the ball to halfway after his late goal, but it was only ever going to be a consolation strike for the Frenchman

Robben rounds Cech and looked certain to add a fifth goal, but the big goalkeeper did just enough to slow down the winger

Mathieu Debuchy get back to deny Robben with a crunching tackle, but Bayern still managed a fifth goal late on

Muller scores his second of the night in the final minute to round off a superb performance by the German champions

Muller celebrates his second goal with Costa, as Wenger's Champions League hopes were left hanging by a thread